add support for Java 26

[monperrus]

Java 26 was officially released last month at JavaOne. You can rewatch the Java 26 launch and the JavaOne keynote here [1].

With JDK 26 released, the focus now shifts to JDK 27 testing. At the time of writing, one JEP already targets JDK 27 (JEP 527: Post-Quantum Hybrid Key Exchange for TLS 1.3). To learn more about post-quantum cryptography, watch this JavaOne session [2] by Sean Mullan (OpenJDK Security Group Lead). I’ll conclude with a big shout-out to the Eclipse Collections team for already identifying a potential issue with JDK 27 early-access builds.

[1] https://www.youtube.com/watch?v=3fLCOqpIfI0
[2] https://www.youtube.com/watch?v=6xh-bN4W74o

[monperrus]

@seinturier nothing to do per your analysis? then close?

[SirYwell]

The easiest is to look at the OpenJDK page https://openjdk.org/projects/jdk/26/. The only JEP affecting the language is JEP 530 which is still in preview, so there are no changes for Spoon.

[seintur]

The last version of JDT (3.45.0) released on 6 March does not provide an option for compliance level 26.

This is only in PR eclipse-jdt/eclipse.jdt.core#4941 merged on 18 March that commit eclipse-jdt/eclipse.jdt.core@5da6027#diff-2fed4875fac9f0fcd5a90619dbcb2121bd88cf87c47319e1cdd17653b95c2e46 introduced the option to run JDT with compliance level 26.

So, in practise, I guess that we may encounter a JDT error if we try to run the current version of Spoon/JDT asking for compliance level 26. Things should be better with the next release of JDT.